The present invention relates to a novel method for preparing functionalized silicone oils with controlled viscosity, containing at least one hydrocarbon ring in which is included an oxygen atom. In particular, the present invention relates to a method of hydrosilylation between polyorganohydrosiloxanes and unsaturated synthons containing at least one hydrocarbon ring in which is included an oxygen atom.
Reactions between polyorganohydrosiloxanes and olefins or acetylenic hydrocarbons are very well known. The polyorganohydrosiloxanes have, for example, the formulae:
Me3SiOxe2x80x94(MeHSiO)nxe2x80x94(Me2SiO)mxe2x80x94SiMe3 in which n and m are integers or fractions such that 1xe2x89xa6nxe2x89xa61000 and 0 less than mxe2x89xa61000;
Me2HSiOxe2x80x94(MeHSiO)oxe2x80x94(Me2SiO)pxe2x80x94SiHMe2 in which o and p are integers or fractions such that 0 less than oxe2x89xa61000 and 0 less than pxe2x89xa61000.
Many synthons can functionalize polyorganohydrosiloxanes; for example, alkenes, styrenes, allyl alcohols, allyloxy ethers or allylamines are used as synthons.
These reactions are very commonly used for the synthesis of functionalized silicone oils, and the oils obtained as applications in very diverse fields such as anti-adhesion and lubrication.
In particular, functionalized oils can be prepared with 1,2-epoxy-4-vinylcyclohexane synthons. By way of application, these functionalized silicone oils are then thermally crosslinked in the presence of an acid catalyst such as hydrochloric acid or sulfuric acid, or photochemically crosslinked in the presence, for example, of a cationic photoinitiator for the preparation of anti-adhesive films for paper and/or plastics.
A very large number of catalytic compositions is used in hydrosilylation reactions. The catalytic compositions most widely known contain metals such as platinum, rhodium, cobalt or palladium. Specific examples of such catalytic compositions are platinum halides and rhodium halides, for example H2PtCl6, PtCl2, (RhCl3.xH2O), complexes of platinum with siloxanes containing unsaturated groups, complexes of platinum with olefins and cationic complexes of platinum with nitrites as ligands.
Generally, the catalytic compositions used in the hydrosilylation reaction are homogeneous catalytic compositions, i.e. said compositions are dissolved in the reaction medium. One of the compositions most widely used is the catalytic Karstedt composition described in particular in U.S. Pat. No. 3,775,452; this Karstedt composition consists of platinum complexes in which the absolute and real degree of oxidation is zero (0), and which are of formula: 
However, during the hydrosilylation reaction according to the methods of the prior art, isomerization reactions of the unsaturated synthons are observed to varying degrees, which makes it necessary to work with a molar excess of synthons relative to the polyorganohydrosiloxane in the reaction medium. This excess in the proportion of synthon causes additional expense for the industrial implementation of the method. It would therefore be desirable to reduce the required proportion of synthon, which would result in a not insignificant saving in terms of the method.
In addition, the hydrosilylation processes of the prior art are relatively unsuitable, or not at all suitable, for hydrosilylation reactions between polyorganohydrosiloxanes and synthons containing a ring in which is included an oxygen atom (epoxide, etc.). The latter, during the hydrosilylation reaction and/or the devolatilization step, have a tendency to open up and to cause uncontrolled reactions of polymerization and of crosslinking (formation of gum and/or resin) of the functionalized oils, which are initiated by the presence of the usual catalytic compositions such as the homogeneous catalytic compositions which also catalyze the polymerization of rings which include an oxygen atom.
In addition, the functionalized silicone oils obtained from usual methods are generally colored, with the order of 120 to 300 hazen, which as a result limits the domains which can be envisioned for their use, in particular in the domain of transparent and anti-adhesive films for paper or for transparent films (for example of the polyester type). This coloration is generally due to the presence in the functionalized oils of metal aggregates or of colloids of nanometric size, derived from the usual catalytic compositions. In these cases, the functionalized silicone oils require additional sets of filtration and purification in order to be usable after crosslinking in the domain of transparent films; these additional steps make industrial implementation expensive and therefore economically relatively nonviable.
The Applicant has developed a novel method for preparing functionalized silicone oils by hydrosilylation, which makes it possible to significantly reduce the isomerization reactions of the unsaturated synthon and to very substantially reduce the opening of the ring including an oxygen atom, present on the unsaturated synthon.
The method used makes it possible to obtain functionalized silicone oils which are less colored than those obtained using a method with a catalyst of the Karstedt type, which makes it possible to limit or eliminate the purification steps. Depending on the case, the oils obtained are transparent and/or translucent and can therefore be used directly in applications requiring these qualities.
In particular, the silicone oils obtained using the method of the invention can be used after crosslinking, in the domain of inks, the domain of varnishes and also in the domain of coatings, in particular films, transparent and/or anti-adhesive, through applications on supports of very varied nature; for example papers, glasses, plastics and/or metals.
According to the hydrosilylation method of the present invention, the polyorganohydrosiloxane is reacted with synthons, which may be different or identical, containing a hydrocarbon ring in which is included at least one oxygen atom. This reaction is carried out in the presence of a catalytic metal complex of formula I: 
in which:
M represents a metal in the 0 oxidation state chosen from the metals of group 8 of the Periodic Table as published in Handbook of Chemistry and Physics, 65th edition, 1984-1985;
X represents O, NRa and/or CRfRg;
Y1 and Y2, which may be identical or different, represent CRbRc and/or SiRdRe;
R1, R2, R5 and R6, which may be identical or different, are chosen from a hydrogen atom, an alkyl group and an aryl group optionally substituted with alkyl;
R3, R4, Ra, Rb, Rc, which may be identical or different, are chosen from a hydrogen atom; an alkyl group; an acyl group; an aryl group optionally substituted with an alkyl; a cycloalkyl group optionally substituted with an alkyl; and an arylalkyl group in which the aryl component is optionally substituted with an alkyl component;
Rd and R, which may be identical or different, are chosen from an alkenyl; an alkynyl; an alkyl; an alkoxy; an acyl; an aryl optionally substituted with an alkyl; a cycloalkyl optionally substituted with an alkyl; and an arylalkyl in which the aryl component is optionally substituted with an alkyl; or else
when Y1 and Y2, which may be identical or different, represent SiRdRe, two groups Rd linked to two different silicon atoms together form:
a chain of formula: 
xe2x80x83which n is an integer from 1 to 3; X is as defined above; R and Rxe2x80x2, which may be identical or different, take any one of the meanings given above for Re, it being understood that, when n is 2 or 3, a single silicon atom of said chain can be substituted with one or two alkenyl or alkynyl groups;
a saturated hydrocarbon chain, the two groups Rd together with said silicon atoms and X forming a 6- to 10-membered ring; or else
when Y1 and Y2, which may be identical or different, represent CRbRc, two groups Rb linked to different carbon atoms together form a saturated hydrocarbon chain, the two groups Rb together with the carbon atoms which bear them and X forming a 6- to 10-membered ring;
Rf and Rg represent, independently of one another, a hydrogen atom; an alkyl group; an acyl group; an aryl group optionally substituted with alkyl; a cycloalkyl group optionally substituted with an alkyl; an arylalkyl group in which the aryl component is optionally substituted with alkyl; a halogen atom; an alkenyl group; an alkynyl group; or a group SiG1G2G3 in which G1, G2 and G3 are, independently of one another, an alkyl; an alkoxy; an aryl optionally substituted with an alkyl or an alkoxy; or an arylalkyl group in which the aryl component is optionally substituted with an alkyl or an alkoxy;
L represents a carbene of formula II: 
xe2x80x83in which:
A and B, which may be identical or different, represent C or N, it being understood that, when A represents N, then T4 represents nothing, and when B represents N, then T3 represents nothing;
T3 and T4, which may be identical or different, represent a hydrogen atom; an alkyl group; a cycloalkyl group optionally substituted with an alkyl or an alkoxy; an aryl group optionally substituted with an alkyl or an alkoxy; an alkenyl group; an alkynyl group; or an arylalkyl group in which the aryl component is optionally substituted with an alkyl or an alkoxy;
T1 and T2, which may be identical or different, represent (i) an alkyl group; (ii) a perfluorinated alkyl group or an alkyl group optionally substituted with a perfluoroalkyl group; (iii) a cycloalkyl group optionally substituted with an alkyl or alkoxy group; (iv) an aryl group optionally substituted with an alkyl or alkoxy group; (v) an alkenyl group; (vi) an alkynyl group; or (vii) an arylalkyl group in which the aryl component is optionally substituted with an alkyl or alkoxy group;
or else T1 and T2, which may be identical or different, represent a monovalent radical of formula (V) below:
xe2x80x83xe2x80x94V1xe2x80x94V2xe2x80x83xe2x80x83(V)
xe2x80x83in which:
V1 is a divalent hydrocarbon radical, preferably an optionally substituted linear or branched C1-C10 alkylene,
V2 is a monovalent radical chosen from the group of the following substituents:
alkoxy, xe2x80x94OR"ugr" with R"ugr" corresponding to hydrogen, alkyl, aryl, amine, preferably N(R"ugr")2 with R"ugr" corresponding to hydrogen, alkyl, aryl,
or else alternatively T1 and T2, which may be identical or different, represent a monovalent radical of formula (W) below:
xe2x80x94W1xe2x80x94xcfx89xe2x80x94W2xe2x80x83xe2x80x83(W)
xe2x80x83in which:
W1 is a divalent hydrocarbon radical, preferably an optionally substituted linear or branched C1-C10 alkylene,
xcfx89 represents:
xe2x80x83xe2x80x94Rxcex1Cxe2x95x90CRxcex1xe2x80x94, with Rxcex1 corresponding to H or an alkyl group
xe2x80x83or
xe2x80x94Cxe2x95x90Cxe2x80x94
W2 is a monovalent radical chosen from the group of the following substituents:
Rxcex2=alkyl, H;
Si-alkyl or Si-alkoxy, preferably xe2x80x94Si(Rxcex4)3 with Rxcex4=alkyl;
alcohol, preferably xe2x80x94C(Rxcex5)2OH with Rxcex5=OH, H or alkyl;
ketone, preferably 
xe2x80x83with Rxcex4=alkyl, alkenyl, alkynyl;
carboxy, preferably 
xe2x80x83with Rxcex4=alkyl, alkenyl, alkynyl;
amide, preferably 
xe2x80x83with Rxcex2=H, alkyl, alkenyl, alkynyl;
acyl, preferably 
xe2x80x83with Rxcex4=alkyl, alkenyl, alkynyl;
or else alternatively the substituents T1, T2, T3 and T4 can form, in pairs, when they are located at two adjacent points in formula II, a saturated or unsaturated hydrocarbon chain.
According to the invention, the degree of oxidation 0 of the metal M is an essential characteristic of the invention.
Preferably, M, a metal of group 8, is chosen from palladium, platinum and/or nickel. According to a more preferential embodiment of the invention, M represents platinum in the 0 oxidation state.
According to the invention, the term xe2x80x9calkylxe2x80x9d is intended to mean a saturated, linear or branched, hydrocarbon chain preferably containing from 1 to 10 carbon atoms, for example from 1 to 8 carbon atoms, better still from 1 to 7 carbon atoms. Examples of alkyl groups are in particular methyl, ethyl, isopropyl, n-propyl, tert-butyl, isobutyl, n-butyl, n-pentyl, isoamyl and 1,1-dimethylpropyl.
According to the invention, the alkyl component of the alkoxy radical is as defined above.
The perfluorinated alkyl radical or alkyl radical optionally substituted with a perfluoroalkyl group preferably has the formula: xe2x80x94(CH2)pxe2x80x94CqF2q+1 in which p represents 0, 1, 2, 3 or 4; q is an integer of 1 to 10; and CqF2q+1 is linear or branched. Preferred examples of this radical are: xe2x80x94(CH2)2xe2x80x94(CF2)5xe2x80x94CF3 and xe2x80x94(CF2)7xe2x80x94CF3.
The expression xe2x80x9carylxe2x80x9d denotes a monocyclic or polycyclic, and preferably monocyclic or bicyclic, aromatic hydrocarbon group containing from 6 to 18 carbon atoms. It should be understood that, in the context of the invention, the expression xe2x80x9cpolycyclic aromatic radicalxe2x80x9d is intended to mean a radical having two or more aromatic rings fused to one another, i.e. having, in pairs, at least two carbons in common. By way of example, mention may be made of phenyl, naphthyl, anthryl and phenanthryl radicals.
The expression xe2x80x9carylalkylxe2x80x9d denotes an alkyl group as defined above, substituted with one or more aryl groups on its hydrocarbon chain, the aryl group being as defined above. Examples thereof are benzyl and triphenylmethyl.
According to the invention, the expression xe2x80x9cacylxe2x80x9d is intended to mean a group Roxe2x80x94COxe2x80x94 in which Ro represents alkyl as defined above; or else a group Arxe2x80x94COxe2x80x94 in which Ar represents an aryl group as defined above, or else arylalkyl in which aryl and alkyl are as defined above and in which the aryl component is optionally substituted with alkyl.
The expression xe2x80x9ccycloalkylxe2x80x9d is intended to mean a monocyclic or polycyclic, preferably monocyclic or bicyclic, saturated hydrocarbon radical preferably containing from 3 to 10 carbon atoms, better still from 3 to 8. The expression xe2x80x9cpolycyclic saturated hydrocarbon radicalxe2x80x9d is intended to mean a radical having two or more cyclic rings attached to one another via "sgr" bonds and/or fused in pairs. Examples of polycyclic cycloalkyl groups are adamantane and norbornane. Examples of monocyclic cycloalkyl groups are cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.
The expression xe2x80x9calkenylxe2x80x9d is intended to mean an unsaturated, linear or branched, hydrocarbon chain exhibiting at least one olefinic double bond, and more preferably a single double bond. Preferably, the alkenyl group contains from 2 to 8 carbon atoms, better still from 2 to 6. Preferred examples of alkenyl groups are vinyl and allyl groups.
According to the invention, the expression xe2x80x9calkynylxe2x80x9d is intended to mean an unsaturated, linear or branched, hydrocarbon chain exhibiting at least one acetylenic triple bond, and more preferably a sole triple bond. Preferably, the alkynyl group contains from 2 to 8 carbon atoms, better still from 2 to 6 carbon atoms. By way of example, mention may be made of the acetylenyl group and also the propargyl group.
According to a preferred embodiment of the invention, Y1 and Y2 either both represent CRbRc, or both represent SiRdRe, such that the preferred compounds of the invention are either of formula I.1 or of formula I.2: 
in which
Rb1 and Rc1 are the substituents Rb and Rc of Y1 in formula I.1;
Rb2 and Rc2 are the substituents Rb and Rc of Y2 in formula I.2;
Rd1 and Re1 are the substituents Rd and Re of Y1 in formula I.1;
and Rd2 and Re2 are the substituents Rd and Re of Y2 in formula I.2.
Thus, Rb1 may be identical to or different from Rc2; Rd1 may be identical to or different from Rd2; and Re1 may be identical to or different from Re2.
Preferably, Rb1=Rb2; Rc1=Rc2; Rd1=Rd2; and Re1=Re2.
Among the latter compounds, those for which R3=R4; R5=R2; and R1=R6 are more preferred.
According to another preferred variant of the invention, Rd1 and Rd2 together form:
(a) either a chain 
xe2x80x83in which n is an integer from 1 to 3; X is as defined above; and R and Rxe2x80x2, which may be identical or different, take any one of the meanings given above for Rc,
(b) or a saturated hydrocarbon chain such that the two substituents Rd, together with the two silicon atoms which bear them and X, form a 6- to 10-membered ring, preferably a 6- to 8-membered ring.
When Rd1 and Rd2 form the chain (a), it is preferred that n is equal to 1 or 2, and more particularly 1, and that R=Re, the two groups Re borne by the two silicon atoms being identical. In this case, Re preferably represents alkyl, for example methyl. More particularly, in these compounds, Rxe2x80x2 represents xe2x80x94CRgxe2x95x90CR1R2 with R1=R6, R2=R5 and R3=R4.
When Rd1 and Rd2 form the chain (b), it is preferred that the two groups Rd, together with the two silicon atoms and the group X, form an 8-membered ring. In this case, it is preferred that Re1 is identical to Re2. These compounds have the general formula: 
in which T represents an alkyl group, i is an integer of between 0 and 5, T being located on one or more of the points 1, 2, 3, 4 and 5 of the formula above.
In the same way, when Y1 and Y2 represent CRbRc, the two groups Rb bonded to different carbon atoms can together form a saturated hydrocarbon chain (c), such that the two groups Rb, together with the carbons which bear them and X, form a 6- to 10-membered ring. Preferably, the ring formed is an 8-membered ring, in which case the metal complex corresponds to the formula: 
in which T represents an alkyl group; i is an integer of between 0 and 5, T being located on one or more of the points 1, 2, 3, 4 and 5 of the formula above.
In the context of the invention, two groups Rd bonded to two different silicon atoms can form a chain of formula: 
When this is the case, it is preferred that X represents O in the compounds of the invention. These preferred compounds have the general formula: 
Among these compounds, it is preferred that Re1=Re2. Advantageously, Re1=Re2 represents alkyl (for example methyl).
The expression xe2x80x9crepresents nothingxe2x80x9d means that the substituents-T3, respectively-T4, are nonexistent. Specifically, in the formulae II, the nitrogen atom is trivalent, such that, when A or B represents N, the nitrogen atom cannot exhibit any additional substituent.
According to a particular embodiment of the invention, the carbenes of formulae II exhibit at least two fused rings, i.e. at least two substituents from T1, T2, T3 and T4, located on two adjacent points, together form a saturated or unsaturated, hydrocarbon chain preferably containing from 3 to 6 carbon atoms. The expression xe2x80x9csaturated or unsaturated, hydrocarbon chainxe2x80x9d is intended to mean a linear or branched, hydrocarbon chain possibly exhibiting one or more unsaturations of the olefinic double bond or acetylenic triple bond type.
When the carbenes II exhibit two fused rings, they therefore correspond to one of the following formulae, in which (alk) represents a saturated or unsaturated, hydrocarbon chain: 
It should be understood, however, that the carbenes II can exhibit more than two fused rings.
When Rf and/or Rg represent SiG1G2G3, it is preferred that Rf and/or Rg are trialkylsilyl, for example SiG1G2G3 in which G1=G2=G3=alkyl.
Subgroups of the metal complexes of the invention consist of the complexes for which:
X=O; Y1 and Y2 independently represent SiRdRe; or
X=NRa; Y1 and Y2 independently represent CRbRc; or
X=NRd; Y1 and Y2 independently represent SiRdRe; or
X=CR1Rg; Y1 and Y2 independently represent CRbRe; or
X=CRfRg; Y1 and Y2 independently represent SiRdRe.
Among these 5 families of metal complexes of formula I, preference is given to those for which:
X=O; Y1 and Y2 independently represent SiRdRe; or
X=NRa; Y1 and Y2 independently represent CRbRc; or
X=CRfRg; Y1 and Y2 independently represent CRbRc.
Very preferably, X=O and Y1 and Y2 independently represent SiRdRe in the metal complex of formula I.
In the context of the invention, the expression xe2x80x9cindependently representxe2x80x9d means that the substituents denoted are either identical or different.
More preferably, R1, R2, R5 and R6 are hydrogen atoms.
Preferred meanings for R3 and R4 are in particular a hydrogen atom; an alkyl group; aryl optionally substituted with alkyl; and cycloalkyl optionally substituted with alkyl. Among these preferred meanings, it is particularly advantageous for R3 and R4 which are identical, to represent a hydrogen atom; (C3-C8)cycloalkyl or (C1-C8)alkyl.
More preferably, the diolefinic ligand of the complex of formula I is symmetrical, i.e. R5=R2; R6=R1; R3=R4 and the two groups Y1 and Y2 are either strictly identical with one another, or Y1=CRb1Rc and Y2=CRb2Re in which Rb1 and Rb2 together form a symmetrical chain, or else Y1=SiRd1Re and Y2=SiRd2Re in which Rd1 and Rd2 together form a symmetrical chain.
A preferred group of complexes according to the invention consists of the complexes of formula I in which L represents a carbene of formula II. Preferably, A and B in the formulae II both represent a carbon atom.
Preferred meanings for T1 and T2 are alkyl; cycloalkyl; arylalkyl; and aryl optionally substituted with alkyl.
Preferred meanings for T3 and T4 are hydrogen; alkyl; cycloalkyl; arylalkyl; and aryl optionally substituted with alkyl.
Preferably, when T1, T2, T3 or T4 represents alkyl, then alkyl is methyl, isopropyl or tert-butyl.
Similarly, when T1, T2, T3 or T4 represents aryl, then aryl is phenyl.
When T1, T2, T3 or T4 represents aryl optionally substituted with alkyl, then T1, T2, T3 or T4 is tolyl or xylyl.
When T1, T2, T3 or T4 represents arylalkyl, then arylalkyl is preferably benzyl or triphenylmethyl.
When T1, T2, T3 or T4 represents cycloalkyl, then cycloalkyl is preferably cyclopentyl, cyclohexyl or adamantyl.
A preferred group of complexes of formula I consists of the complexes for which, in the carbene of formulae II, T3 and T4 represent a hydrogen atom.
Similarly, the complexes of formula I in which T1 and T2 are chosen from (C1-C8)alkyl and (C3-C8)cycloalkyl form a preferred subgroup. Better still, T1 and T2 are identical and represent (C3-C8)cycloalkyl.
Advantageously, T1 and T2, which may be identical or different, represent (C1-C8)alkyl or (C3-C8)cycloalkyl; or else R3 and R4, which may be identical or different, represent (C1-C8)alkyl or (C3-C8)cycloalkyl; or else alternatively T1, T2, R3 and R4, which may be identical or different, represent (C1-C8)alkyl or (C3-C8)cycloalkyl.
A particularly preferred group of the metal complexes of formula I consists of the complexes of formula: 
in which:
R3 represents a hydrogen atom; a (C1-C8)alkyl group; or a (C3-C8)cycloalkyl group optionally substituted with (C1-C4)alkyl;
T1 and T2 are identical and, represent (C1-C8)alkyl or (C3-C8)cycloalkyl;
Rd and Re are as defined above.
Other preferred subgroups of the invention are defined as follows:
metal complexes of formula I in which Y1 and Y2, which are identical, represent SiRdRe; R1=R2=R3=R4=R5=R6=H; X=O; Rd and Re are independently chosen from alkyl; aryl optionally substituted with alkyl; alkenyl; and alkynyl;
metal complexes of formula I in which Y1 and Y2, which are identical, represent SiRdRe; X=O; R1=R6; R2=R5; R3=R4; R1 and R2 independently represent alkyl; R3 represents alkyl or aryl optionally substituted with alkyl; Rd and Re independently represent alkyl; alkenyl; alkynyl; or aryl optionally substituted with alkyl;
metal complexes of formula I in which Y1 and Y2, which are identical, represent SiRdRe; X=O; R1=R2=R3=R4=R5=R6=H; and Rd=Re=methyl or else Rd=methyl and Re=phenyl;
metal complexes of formula I in which Y1 and Y2, which are identical, represent SiRdRe; X=O; R1=R3=R4=R6=H; R2=R5=alkyl;
metal complexes of formula I in which Y1 and Y2, which are identical, represent SiRdRe; X=CRfRg; Rf=Rg=a hydrogen atom; Rd and Re, which may be identical or different, are chosen from alkyl; and aryl optionally substituted with alkyl; R1=R6; R2=R5; R3=R4; R1 and R2 are chosen from a hydrogen atom and an alkyl group; R3 represents a hydrogen atom, alkyl or aryl optionally substituted with alkyl;
metal complexes of formula I in which Y1 and Y2, which are identical, represent SiRdRe; X=CRfRg in which Rf and Rg represent a halogen atom, preferably a chlorine atom or a bromine atom; Rd=Re=alkyl, preferably methyl; R1=R2=R3=R4=R5=R6=H;
metal complexes of formula I in which Y1 and Y2, which are identical, represent SiRdRe; X=CRfRg in which Rf and Rg represent SiG1G2G3 such as trialkylsilyl (for example Si(CH3)3); Rd=Re=alkyl, preferably methyl; R1=R2=R3=R4=R5=R6=H;
metal complexes of formula I in which X represents xe2x80x94NRa; Y1 and Y2, which are identical, represent SiRdRe; R1=R6; R2=R5; R3=R4;
metal complexes of formula I in which X represents NRa; Y1=Y2=SiRdRe; the two groups Rd together form the chain xe2x80x94NRaxe2x80x94(SiReRdoxe2x80x94NRa)nxe2x80x94 in which Rdo represents xe2x80x94CR3xe2x95x90CR1R2; n represents from 1 to 3; R1=R6; R2=R5; and R3=R4.
The complexes of the invention are prepared conventionally, for example from known complexes of the state of the art, by ligand exchange, i.e. by addition of the appropriate carbene of the formula II to a metal complex of the metal M, in solution, denoted precursor complex.
Suitable precursor complexes are the Karstedt complex of formula:
Pt2[ViMe2Sixe2x80x94Oxe2x80x94SiMe2Vi]3 in which Vi represents the vinyl radical; and more generally M2[R5R6Cxe2x95x90CR4xe2x80x94Y1xe2x80x94Xxe2x80x94Y2xe2x80x94CR3xe2x95x90CR1R2]3 in which M, R5, R6, R4, R3, R1, R2, Y1, X and Y2 are as defined previously, such as for example:
xe2x80x83M2[CR5R6xe2x95x90CR4SiRdRexe2x80x94Oxe2x80x94SiRdRexe2x80x94CR3xe2x95x90CR1R2]3, it being understood that M, R1, R2, R3, R4, R5, R6, Rd and Re are as defined above;
Pt(COD)2 in which COD represents cyclooctadiene, and more generally M(COD)2 in which M is a metal from group 8; or else
metal complexes of olefin and bisphosphine.
The complexes of formula I are generally prepared from precursor complexes having, as ligand, at least one diolefinic compound of formula III: 
in which R1, R2, R3, R4, R5, R6, X, Y1 and Y2 are as defined above for formula I.
These ligands are either commercially available or are easily prepared by those skilled in the art from commercial compounds.
When X represents NR4 and Y1 and Y2, independently of one another, represent CRbRc, the compounds of formula III are commercially available amines or amines prepared in a manner known in itself from commercially available compounds.
When X represents O and Y represents CRbRc, the compounds of formula III are ethers. These ethers are commercially available or are prepared in a manner known in itself from commercially available compounds.
The compounds of formula III in which X represents CRfRg and Y represents CRbRc are diolefins which are readily accessible to those skilled in the art by synthesis or which are commercially available.
The compounds of formula III in which X represents NRa in which Ra represents H or alkyl; R1=R6; R2=R5; R3=R4; and Y1=Y2=SiRdRe can be prepared by the action of an amine Raxe2x80x94NH2 with two equivalents of a silyl chloride of formula: ClSiRdRexe2x80x94CR3xe2x95x90CR1R2 in which Re, Rd, R1, R2 and R3 are as defined above.
The compounds of formula III in which X represents NRa, Ra being as defined above in formula I; Y1=Y2=SiRdRe in which Re is as defined above in formula I; the two groups Rd together form the chain: xe2x80x94NRaxe2x80x94(SiReRdoxe2x80x94NRa)nxe2x80x94in which Ra and Re are as defined above; n represents an integer from 1 to 3; Rdo represents xe2x80x94CR3xe2x95x90CR1R2; R1=R6; R2=R5 and R3=R4, can be prepared by reaction of the amine Raxe2x80x94NH2 with the silyl chloride of formula: Cl2SiRexe2x80x94CR3xe2x95x90CR1R2 in which Re, R1, R2 and R3 are as defined above.
The compounds of formula III in which X represents O, and Y1 and Y2 represent SiRdRe are linear, branched or cyclic siloxanes which are commercially available or the preparation of which is possible from commercial compounds, using the conventional methods of the state of the art. Examples of preferred siloxanes of formula III are ViMe2SiOSiMe2Vi and (MeViSiO)3, the second formula representing a cyclosiloxane in which Vi represents vinyl.
In the case of the symmetrical compounds of formula III, i.e. those for which R1=R6; R2=R5; R3=R4 and Y1=Y2, one of the following synthesis variants may be implemented.
(Variant a): To prepare said symmetrical siloxanes of formula III for which R1, R2, R3, Rd and Re are independently chosen from alkyl, aryl, alkenyl and alkynyl, a silyl chloride of formula Cl2SiRdRe can be reacted with an organometallic compound of formula: CR1R2xe2x95x90CR3xe2x80x94Mgxe2x80x94Hal in which R1, R2 and R3 are as defined above and hal represents a halogen atom, under the usual conditions for reaction involving magnesium compounds.
(Variant b): To prepare said symmetrical siloxanes of formula III in which R1=R2=R3=H, and Rc and Rd are chosen from alkenyl, alkynyl, aryl and alkyl, a silyl chloride of formula Cl2SiRdxe2x80x94CHxe2x95x90CH2 can be reacted with an organometallic compound of formula: Rexe2x80x94Mg-hal in which Re is as defined above and hal represents halogen.
To implement this variant, those skilled in the art may refer to J. Gen. Chem., USSR, 1977, 47, 1402-1406.
(Variant c): To prepare said symmetrical siloxanes of formula III in which R1=R3=H and R2 represents alkyl, a siloxane of formula: Hxe2x80x94SiRdRaxe2x80x94Oxe2x80x94SiRdRaH can be reacted with two equivalents of an acetylenic hydrocarbon of formula Hxe2x80x94Cxe2x95x90Cxe2x80x94R2 in which R2 is as defined above.
Cyclic siloxanes of formula III are described in U.S. Pat. No. 4,593,084.
The compounds of formula III in which X represents CRfRg and Y1 and Y2 independently represent xe2x80x94SiRdRe can be prepared using a method similar to one of those described in:
J. of Organometallic Chemistry, 1996, vol. 521, 99-107 (which method is more particularly suitable for preparing the symmetrical compounds of formula III in which Y1=Y2; Rf=Rg=H; Rd and Re represent alkyl or aryl optionally substituted with alkyl; R3 represents a hydrogen atom; alkyl; or aryl optionally substituted; and R1 and R2 are chosen from a hydrogen atom and alkyl);
J. of Organometallic Chemistry, 1997, vol. 545-546, 185-189 (which method is more particularly suitable for preparing symmetrical compounds of formula III in which Y1=Y2; Rf=Rg=Cl or Br; Rd and Re represent alkyl; R1=R2=R3=a hydrogen atom);
J. Chem. Soc., Perkin Trans II, 1987, p. 381 (which method is more particularly suitable for preparing the symmetrical compounds of formula III in which Y1=Y2; Rf=Rg=SiG1G2G3; Rd and Re represent alkyl; R1=R2=R3=a hydrogen atom).
The carbenes of formula II can be prepared by deprotonation of imidazolium salts, of tetrazolium salts, of triazolium salts, or of pyrazolium salts, as appropriate, under the action of a base.
These reactions can be represented schematically as follows: 
In these reaction schemes, T1, T2, T3, T4, A and B are as defined above for formula I and Xxe2x88x92 represents an anion.
The nature of the anion Xxe2x88x92 is not critical according to the invention. The anion Xxe2x88x92 is the anion derived from an organic or inorganic Brxc3x6nsted acid (protic acid). Conventionally, the anion Xxe2x88x92 is derived from an acid having a pKa of less than 6. Preferably, Xxe2x88x92 is derived from an acid with a pKa of less than 4, better still less than 2. The pKas to which reference is made here are the pKas of the acids as measured in water.
Examples of acids are the carboxylic acids of formula Goxe2x80x94COOH in which Go represents alkyl, and for example (C1-C22)alkyl; or else aryl, and for example (C8-C18)aryl optionally substituted with one or more alkyl(s), preferably one or more (C1-C6)alkyl(s); the sulfonic acids of formula Goxe2x80x94SO3H in which Go is as defined above; and the phosphonic acids of formula Goxe2x80x94PO3H in which Go is as defined above; other acids are HF, HCl, HBr, Hl, H2SO4, H3PO4 and HClO4.
Preferred examples of carboxylic acids are acetic acid, benzoic acid and stearic acid. As a preferred sulfonic acid, mention will be made of benzenesulfonic acid and, as a preferred phosphonic acid, mention will be made of phenylphosphonic acid.
According to the invention, the Xxe2x88x92 anions derived from the acids HF, HCl, HBr, Hl, H2SO4 and H3PO4 are more particularly preferred.
Thus, anions Xxe2x88x92 which are particularly preferred according to the invention are the halide, sulfate, hydrogen sulfate, phosphate, hydrogen phosphate and dihydrogen phosphate anions. Tetrafluoroborates and hexaphenyl phosphates may also be mentioned as anions.
The bases which can be used for the deprotonation of the salts of formula VIII.1 are strong bases chosen from alkali metal hydrides, alkali metal hydroxides, alkali metal carboxylates, alkali metal alkoxides and alkali metal amides.
Examples of a suitable base are therefore sodium hydride, potassium hydroxide, sodium methoxide, potassium tert-butoxide, lithium diisopropylamide and mixtures thereof.
The deprotonation reaction is preferably carried out in a solvent capable of dissolving the starting salt of formula VIII.1, and also the other reagents.
Generally, the reaction temperature is between 40xc2x0 C. and xe2x88x9278xc2x0 C., preferably between 30 and xe2x88x9250xc2x0 C., better still between 25 and xe2x88x9240xc2x0 C., for example between 20 and xe2x88x9230xc2x0 C.
Solvents which can be used in the method for preparing the carbenes are cyclic or noncyclic ethers, such as diethyl ether, diisopropyl ether, tetrahydrofuran, dioxane, dimethoxyethane or diethylene glycol dimethyl ether. Other solvents which can be used are dimethyl sulfoxide, dimethylformamide, dimethylacetamide, hexamethylphosphorylamide: [(CH3)2N]3PO and hexamethylphosphoramide [(CH3)2N]3P.
The carbenes of formula II in which A and B both represent a carbon atom can also be prepared by reduction of the corresponding thiones of formula IX: 
This reaction was described by N. Kuhn in Synthesis, 1993, 561. Preferably, the reduction is carried out in a solvent of the ether or amide type, as defined above, at a temperature of between 50 and 150xc2x0 C., in the presence of potassium.
As regards the starting salts of formula (VIII.1), they can be prepared by reaction of the corresponding imidazoles, pyrazoles, triazoles and tetrazoles with an appropriate acid.
The nature of the anion Xxe2x88x92 in the salts of formula (VIII.1) depends on the acid used in this step. The acids which can be used are, for example, those which are listed above and from which Xxe2x88x92 derives.
Another method for synthesizing the salts of formula (VIII.1) in which A=B=C is described in U.S. Pat. No. 5,077,414.
This method comprises reacting an xcex1-dicarbonyl compound (X) of formula: 
in which T3 and T4 are as defined above, with HCHO and two amines of formulae T1xe2x80x94NH2 and T2xe2x80x94NH2 in the presence of an appropriate acid.
Other methods for preparing the salts of formula (VIII.1) are provided in Chem. Eur. J. 1996, 2, No. 12, pages 1627-1636 and Angew. Chem. Int. Ed. Engl. 1997, 36, 2162-2187.
The compounds of formula (IX) can be prepared by condensation of an appropriate thiourea of formula (XI): 
with an xcex1-hydroxy ketone of formula (XII): 
xe2x80x83in which T1, T2, T3 and T4 are as defined above. Suitable operating conditions are in particular described by N. Kuhn in Synthesis, 1993, 561.
According to a particularly preferred embodiment of the invention, the metal complex of the invention has the formula: 
in which L is as defined above.
A simple method for preparing this complex consists in reacting the carbene L with the Karstedt catalyst of mean formula Pt2[ViMe2Sixe2x80x94Oxe2x80x94SiMe2Vi]3 in which Vi represents the vinyl radical.
This reaction can be carried out with or without a solvent.
Examples of suitable solvents are cyclic or noncyclic ethers, such as diethyl ether, diisopropyl ether, tetrahydrofuran, dioxane, dimethoxyethane or diethylene glycol dimethyl ether; amides such as dimethylformamide or dimethylacetamide; and aromatic hydrocarbons (such as toluene, xylenes and more particularly toluene).
Advantageously, the reaction is carried out in an ether, and preferably in tetrahydrofuran.
The reaction temperature conventionally ranges between 10 and 50xc2x0 C., preferably between 15 and 35xc2x0 C., very preferably between 20 and 25xc2x0 C.
It is preferable to work in the presence of a slight excess of carbene relative to the platinum. Thus, the molar ratio of the carbene L to the platinum generally ranges between 1 and 1.3, preferably between 1 and 1.1.
A simple way in which to carry out the procedure consists in pouring a solution of carbene, at the appropriate temperature, into a solvent, in a reactor containing a solution of the Karstedt catalyst in this same solvent.
The molarity of the solutions of carbene and of catalyst is not critical according to the invention.
The synthons contain at least one hydrocarbon ring in which is included an oxygen atom, and have the formula: 
in which:
(i) the symbols Z, which may be identical or different, correspond to a divalent hydrocarbon radical chosen from the linear or branched alkylene radicals containing from 1 to 12 carbon atoms, one of the symbols Z possibly being a free valency;
(ii) the symbol U corresponds to a free valency or a divalent radical chosen from the linear or branched alkylene radicals containing from 1 to 12 carbon atoms and possibly containing a hetero atom, preferably an oxygen atom;
(iii) the symbol R8 corresponds to a hydrogen atom or monovalent hydrocarbon radical chosen from the linear or branched alkyl radicals containing from 1 to 12 carbon atoms, and preferably a hydrogen atom or a methyl radical; 
xe2x80x83in which:
(i) the symbols Z, which may be identical or different, correspond to a divalent hydrocarbon radical chosen from the linear or branched alkylene radicals containing from 1 to 12 carbon atoms, one of the symbols Z possibly being a free valency;
(ii) the symbol U corresponds to a free valency or a divalent radical chosen from the linear or branched alkylene radicals containing from 1 to 12 carbon atoms and possibly containing a hetero atom, preferably an oxygen atom;
(iii) the symbol R8 corresponds to a hydrogen atom or monovalent hydrocarbon radical chosen from the linear or branched alkyl radicals containing from 1 to 12 carbon atoms, and preferably a hydrogen atom or a methyl radical;
and 
xe2x80x83in which:
(i) the symbols Z, which may be identical or different, correspond to a divalent hydrocarbon radical chosen from the linear or branched alkylene radicals containing from 1 to 12 carbon atoms and possibly containing at least one hydroxyl function; one of the symbols Z possibly being a free valency for (XVII) and the two symbols Z can be simultaneously a free valency for (XVIII);
(ii) the symbols Zxe2x80x2, which may be identical or different, correspond to a divalent hydrocarbon radical chosen from the linear or branched alkylene radicals containing from 1 to 12 carbon atoms; at least one of the symbols Zxe2x80x2 possibly being a free valency;
(iii) the symbol U corresponds to a free valency or a divalent radical chosen from the linear or branched alkylene radicals containing from 1 to 12 carbon atoms, and possibly containing a hetero atom, preferably an oxygen atom;
(iv) the symbol R8 corresponds to a hydrogen atom or monovalent hydrocarbon radical chosen from the linear or branched alkyl radicals containing from 1 to 12 carbon atoms, and preferably a hydrogen atom or a methyl radical.
Preferably, the hydrocarbon ring in which is included the hydrogen atom contains at most 8 atoms in said ring. In addition, the best results are obtained in accordance with the hydrosilylation method of the invention with synthons containing only one hydrocarbon ring in which is included an oxygen atom. In particular, the synthons used which give good results (see examples below) have the formula: 
In general, the synthons which react with the polyorganohydrosiloxane are identical synthons. The polyorganohydrosiloxane/synthons molar ratio is between 0.01 and 100, preferably between 0.1 and 10.
The polyorganohydrosiloxanes used in the methods according to the invention are very diverse in nature. These polyorganohydrosiloxanes may be linear or cyclic and have the mean formulae: 
in which:
the symbols R7 are identical or different and correspond to a monovalent hydrocarbon radical chosen from the phenyl radical and the linear or branched alkyl radicals containing from 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms;
the symbols Xxe2x80x2 are identical or different and correspond to a monovalent radical chosen from R7, a hydrogen atom, a methoxy radical and an ethoxy radical;
a and b are integers or fractions, such that:
0 less than axe2x89xa6200, preferably 0 less than axe2x89xa699
0xe2x89xa6bxe2x89xa6200, preferably 1 less than bxe2x89xa6100, and at least one of the two Xs corresponding to the hydrogen radical if b=0;
5 less than a+bxe2x89xa6200, preferably 10 less than a+bxe2x89xa6100
c and d are integers or fractions, such that
0 less than c less than 5, preferably 0 less than c less than 3
1 less than d less than 10, preferably 1 less than d less than 5,
3 less than a+b less than 10, preferably 3 less than a+b less than 5
The method according to the invention can be implemented according to various variants. By way of example, it is possible to use a first implementation in which all of the reagents and the catalytic composition are mixed in the reaction medium (batch type).
In the context of its experimental trials, the Applicant has developed an advantageous method in accordance with the first implementation. This method of hydrosilylation between a polyorganohydrosiloxane and an unsaturated synthon comprises the following steps:
(a) an amount of 5 to 5 000 ppm, preferably of 10 to 100 ppm, of catalytic metal complex relative to the total mass of the reagents is introduced, under inert gas, into the reaction medium;
(b) the synthon is introduced into the reaction medium;
(c) said medium is heated to a temperature of between 25xc2x0 C. and 200xc2x0 C., and preferably between 50xc2x0 C. and 160xc2x0 C;
(d) the polyorganohydrosiloxane is then introduced over a period of between 0 and 24 hours, preferably between 2.5 and 5 hours, the synthon/silicone molar ratio being between 1 and 1.10;
(e) the functionalized silicone oil is finally devolatalized.
This advantageous method can be carried out in bulk, which means that the reaction between the polyorganohydrosiloxane and the synthon takes place in the absence of solvent. However, many solvents, such as toluene, xylene, octamethyltetrasiloxane, cyclohexane or hexane, can be used.
The heterocycles of the oils obtained are virtually unpolymerized after hydrosilylation.
It should be noted that the oils prepared in accordance with the methods according to the invention exhibit lower levels of coloration and of turbidity than those prepared from the same raw materials using a catalyst of the Karstedt type. In particular cases, the oils obtained according to the invention are non-turbid and/or colorless. In the context of our invention, the expression xe2x80x9czero colorationxe2x80x9d is intended to mean a coloration of less than 90 hazen, and preferably less than 40 hazen. As regards the turbidity, the oils are non-turbid when their turbidity is less than 1 NTU and/or they now exhibit only minimal traces of turbidity.
The measured epoxy content of the oils obtained according to the invention is very high and the measured epoxy content/theoretical epoxy content ratio is between 0.95 and 1, this theoretical epoxy content corresponding to the content of xe2x89xa1SiH measured on the polyorganohydrosiloxane before reaction. This demonstrates that the method makes it possible to obtain a product with controlled viscosity (absence of phenomenon of gelling due to the epoxy functions).
The silicone oils according to the invention, because of their properties, are therefore used as an additive (for example as a diluent) or as a main component (for example as a resin) for the preparation of crosslinkable compositions used to prepare inks, varnishes and/or transparent and colorless coatings. In general, these crosslinkable compositions comprise a photoinitiator, a resin which is organic and/or silicone with epoxy and/or acrylate functionality; in addition, these compositions can comprise a diluent and/or a solvent. These compositions are crosslinkable, as appropriate, for example under UV radiation and/or under an electron beam.